from math import hypot
 
x1, y1, x2, y2 = map(float, input().strip().split())
print(hypot(x2 - x1, y2 - y1)) from math import hypot x1, y1, x2, y2 = map(float, input().strip().split()) x1 map(float, input().strip().split()) map float input().strip().split() ().strip().split ().strip() ().strip () input strip split y1 x2 y2 print(hypot(x2 - x1, y2 - y1)) print hypot(x2 - x1, y2 - y1) hypot x2 - x1 x2 x1 y2 - y1 y2 y1 x2, y2 = map(float, input().strip().split()) map(float, input().strip().split()) x2 y2 = map(float, input().strip().split()) map(float, input().strip().split()) y2 y1, x2, y2 = map(float, input().strip().split()) map(float, input().strip().split()) y1 x1, y1, x2, y2 = map(float, input().strip().split()) map(float, input().strip().split()) x1
from math import hypot
 
x1, y1, x2, y2 = map(float, input().strip().split())
print(hypot(x2 - x1, y2 - y1))